Which of the following complexes give white ppt when treated with aqueous solution of \(BaCl_2\)?

A. \([Co(NH_3)_5SO_4]Cl\)

B. \([Co(NH_3)_5Cl]SO_4\)

C. \([Co(NH_3)_5(NO_2)](NO_2)_2\)

D. \([Co(NH_3)_5CN]SO_4\)

Choose the correct answer from the options given below:

B, D only

The correct answer is option 2. B, D only.

The given condition falls under the category of wet test for acid radical, specifically, test for sulfate ion \((SO_4^{2-})\).

The sulfate test using \(BaCl_2\) is a common qualitative test used to detect the presence of sulfate ions (\(SO_4^{2-}\)) in a solution. When a solution containing sulfate ions is treated with a solution of barium chloride (\(BaCl_2\)), a white precipitate of barium sulfate (\(BaSO_4\)) is formed if sulfate ions are present.

The chemical reaction involved is:

\[ BaCl_2 (aq) + SO_4^{2-} (aq) \rightarrow BaSO_4 (s) + 2Cl^- (aq) \]

The white precipitate of barium sulfate (\(BaSO_4\)) is insoluble in water and can easily be observed as a white solid settling at the bottom of the test tube or as a cloudy appearance in the solution.

This test is commonly used to detect the presence of sulfate ions in water samples, as well as in qualitative analysis procedures in chemistry laboratories.

In the context of forming a white precipitate with \(BaCl_2\) in the given complexes:

A. \([Co(NH_3)_5SO_4]Cl\): This complex contains sulfate ions (\(SO_4^{2-}\)) as a ligand. When treated with \(BaCl_2\), it will form a white precipitate of \(BaSO_4\).

B. \([Co(NH_3)_5Cl]SO_4\): This complex contains sulfate ions (\(SO_4^{2-}\)) as a counter ion. Therefore, it will form a white precipitate of \(BaSO_4\) with \(BaCl_2\).

C. \([Co(NH_3)_5(NO_2)](NO_2)_2\): This complex does not contain sulfate ions. Therefore, it will not form a white precipitate with \(BaCl_2\).

D. \([Co(NH_3)_5CN]SO_4\): This complex contains sulfate ions (\(SO_4^{2-}\)) as a counter ion. When treated with \(BaCl_2\), it will form a white precipitate of \(BaSO_4\).

Thus, the complexes that give white precipitate when treated with aqueous \(BaCl_2\) solution are:

B. \([Co(NH_3)_5Cl]SO_4\) and D. \([Co(NH_3)_5CN]SO_4\)

So, the correct answer is option2. B, D only